This application relates to the useful manipulation of magnetic components found in toners as commonly utilized in various printer and electrostatographic print environments. More specifically, the present disclosure relates to at least one realization of magnetic encoding of data elements or magnetic marks in combination with distraction patterns.
To detect counterfeiting, various document security systems are available. For example, watermarking is a common way to ensure security in digital documents. Many watermarking approaches exist with different trade-offs in cost, fragility, robustness, etc. One prior art approach is to use special ink rendering where the inks are invisible under standard illumination. These inks normally respond to light outside the visible range and thereby may be made visible. Examples of such extra-spectral techniques are UV (ultra-violet) and IR (infrared). This traditional approach is to render the encoded data with special inks that are not visible under normal light, but that have strong distinguishing characteristics under the special spectral illumination. Determination of the presence or absence of such encoding may be thereby subsequently performed using an appropriate light source and detector. One example of this approach is found in U.S. Pat. No. 7,614,558 to Katsurabayashi et al. However, these special inks and materials are often difficult to incorporate into standard electro-photographic or other non-impact printing systems like solid ink printers, either due to cost, availability or physical/chemical properties. This in turn discourages their use in variable data printing arrangements, such as for redeemable coupons or other personalized printed media for example.
Another approach taken is a document where copy control is provided by digital watermarking, as for example in U.S. Pat. No. 5,734,752 to Knox, where there is provided a method for generating data encoding in the form of a watermark in a digitally reproducible document which are substantially invisible including the steps of: (1) producing a first stochastic screen pattern suitable for reproducing a gray image on a document; (2) deriving at least one stochastic screen description that is related to said first pattern; (3) producing a document containing the first stochastic screen; (4) producing a second document containing one or more of the stochastic screens in combination, whereby upon placing the first and second document in superposition relationship to allow viewing of both documents together, correlation between the first stochastic pattern on each document occurs everywhere within the documents where the first screen is used, and correlation does not occur where the area where the derived stochastic screens occur and the image placed therein using the derived stochastic screens becomes visible.
With each of the above patents and citations, and those mentioned below, the disclosures therein are totally incorporated by reference herein in their entirety for their teachings.